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Vintage threads from the first ten years

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Re: Peavey Classic 30 mods for playing harmonica?


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1/6/2005 6:19 PM
Mr. Droopy-Drawers
Re: Peavey Classic 30 mods for playing harmonica?
The capacitor 'tricks' I knew about, but not the PI 'trick'. I'll have to try it. And here I have had really fussy people wait for days while I tested tested hundreds of PI tubes to try and find a balanced tube ;). It's a good thing I didn't invest in that tube curve tracer. That's just more of my Grandpa's philosophy; one man's escargot is another man's garden pest. You just never know what it'll sound like for guitar, and if a guitar player would like it. I have had many guys pick up an amplifier that I changed the output tubes, and they ask what I did to ruin their sound! One tube may have been really flat; I just did a JCM800 where one EL34 was idling away at 35mA, while the other was dragging its' butt at 14mA! And, guess what? When I changed the tubes for the guy (with fresh Siemen's no less), he complained. "My sound is gone, my sound is gone!"
 
1/7/2005 3:22 PM
Rick Erickson

quote:
""My sound is gone, my sound is gone!""
 
 
I was testing a Bassman head after repairing it and thought to myself - this is a great tone but it isn't what a Bassman is supposed to do. Turns out one of the "Matched" power tubes way off in bias current. I replaced the pair and rebiased them and the Fender punch was back but that smooth "British" distortion sound was gone.  
 
RE
 
1/7/2005 4:38 PM
Mr. Droopy-Drawers

I have a feeling the Marshall 'magic' is a poorly balanced OPT, and the dynamic current draw is very disparate. I'm not talking about the static current draw; I mean the current 'tracking' in each tube as the signal is applied.
 

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